Their tasks include installing two cameras - belonging to Canadian company UrtheCast - on the hull to photograph the Earth as a part of a commercial venture to create downloadable footage for PC, tablets and smartphones.

The pair will also mount a platform designed to anchor the feet of astronauts during spacewalks, allowing them to have both hands free.

Kotov and Ryazanskiy likewise plan to remove a seismic activity sensor that has been on the hull of the ISS for five years and replace it with new equipment to monitor earthquakes.

The two NASA astronauts now aboard the ISS, Rick Mastracchio and Mike Hopkins, made two emergency spacewalks during the last week to replace a faulty cooling pump on the station's exterior.